From 56990b18d914b8150c9f777d134724d2b3390360 Mon Sep 17 00:00:00 2001
From: Vladislav Vaintroub <wlad@mariadb.com>
Date: Mon, 20 Jul 2020 08:08:00 +0200
Subject: [PATCH] MDEV-23224 better defaults for Windows native threadpool
 implementation

---
 sql/threadpool_win.cc | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/sql/threadpool_win.cc b/sql/threadpool_win.cc
index 515bf0e02bc..df8a6c216a3 100644
--- a/sql/threadpool_win.cc
+++ b/sql/threadpool_win.cc
@@ -30,6 +30,7 @@
 #include <debug_sync.h>
 #include <threadpool.h>
 #include <windows.h>
+#include <set_var.h>
 
 #include "threadpool_winsockets.h"
 
@@ -345,12 +346,24 @@ int TP_pool_win::init()
   InitializeThreadpoolEnvironment(&callback_environ);
   SetThreadpoolCallbackPool(&callback_environ, pool);
 
-  if (threadpool_max_threads)
+  if (IS_SYSVAR_AUTOSIZE(&threadpool_max_threads))
+  {
+    /*
+     Nr 500 comes from Microsoft documentation,
+     there is no API for GetThreadpoolThreadMaxThreads()
+    */
+    SYSVAR_AUTOSIZE(threadpool_max_threads,500);
+  }
+  else
   {
     SetThreadpoolThreadMaximum(pool, threadpool_max_threads);
   }
 
-  if (threadpool_min_threads)
+  if (IS_SYSVAR_AUTOSIZE(&threadpool_min_threads))
+  {
+    SYSVAR_AUTOSIZE(threadpool_min_threads,1);
+  }
+  else
   {
     if (!SetThreadpoolThreadMinimum(pool, threadpool_min_threads))
     {
@@ -359,6 +372,18 @@ int TP_pool_win::init()
     }
   }
 
+
+  if (IS_SYSVAR_AUTOSIZE(&global_system_variables.threadpool_priority))
+  {
+    /*
+     There is a notable overhead for "auto" priority implementation,
+     use "high" which handles socket IO callbacks as they come
+     without rescheduling to work queue.
+    */
+    SYSVAR_AUTOSIZE(global_system_variables.threadpool_priority,
+                    TP_PRIORITY_HIGH);
+  }
+
   TP_POOL_STACK_INFORMATION stackinfo;
   stackinfo.StackCommit = 0;
   stackinfo.StackReserve = (SIZE_T)my_thread_stack_size;